[c2fer]

I have a small dilemma. I have a Western Digital MyBook that I've backed up my iMac (OS X 10.4.10) to a couple of times now using SuperDuper! I thought everything went well both times.
Upon attempting to back-up today, I discovered that my iMac won't run without the MyBook attached to the iMac and running. When attempting to back-up the "to" drop down list in SuperDuper grays out the MyBook drive (which the SuperDuper! instructions tell me means that the external drive is now my start-up drive). I have no idea how/why this happend.
I'm not sure what to do from here. I have different data on the iMac harddrive v. the MyBook, so if I copy over the MyBook to the iMac this might cause me some problems. My current line of thinking is that I need to copy the system files over to the iMac and hope that the iMac will then become the start-up drive (as it should be). But in the end, I'm pretty clueless about how to extricate myself from this situation and hoped someone would have some prescriptive advice for me.